1. Field of the Invention
The present invention relates to the measurement of properties of molten metals and is particularly applicable to steel manufacturing.
2. Description of the Related Art
During steel manufacturing, it often is desirable to know the temperature, composition or other physical property of the molten steel in the furnace. However, directly measuring such properties typically is difficult, due both to the very high temperature of the molten metal and to the existence of a layer of slag, which forms on top of the molten metal and the gaseous environment above the layer of slag.
The most common conventional approach to measuring properties of a molten metal is to insert a lance directly into the molten metal bath. For example, when measuring temperature the lance typically will be provided with one or more thermocouples and immersed through the slag and into the molten metal. Unfortunately, due to the high temperature of the molten metal, such lances usually degrade quickly, making such measurements difficult and expensive to obtain.
What is needed, therefore, is a quick, relatively inexpensive technique for measuring properties of molten metal.
Generally speaking, the present invention addresses this need by using a stream of gas to open a hole through the slag layer, the gaseous layer and/or any other interference matter, thus permitting remote sensing of various properties of the molten metal. In one particular aspect, the invention is directed to the sensing of a property of a molten metal that lies beneath a layer of interfering matter. A stream of gas is propelled into the layer of interfering matter at a velocity that is sufficient for the gas to penetrate through the layer of interfering matter and into the molten metal, thereby providing an opening through the layer of interfering matter. At the same time, energy emanating from the molten metal is detected and measured through the opening, so as to obtain an energy measurement. Then, the energy measurement is processed to determine a value for the desired property of the molten metal.
By virtue of this arrangement, a property of the molten metal can be measured without the necessity of immersing a probe into the molten metal itself. As a result, it generally will be possible to reuse the sensor for a far greater number of measurements than would be possible with conventional sensors.
According to one embodiment of the above technique, the temperature of the molten metal is measured by sensing the infrared radiation emanating from the molten metal, or by using any similar pyrometric evaluation technique. In addition to passively detecting radiation from the molten metal, a sensor assembly can be utilized that includes both a sensor and a source of probe energy, whereby the sensor detects and measures the molten metal""s response to such probe energy. For example, a laser and corresponding sensor might be provided for the performance of laser-induced breakdown spectroscopy.
In a further aspect, the invention is directed to the sensing of a property of a molten metal that lies beneath a layer of interfering matter. A stream of gas is propelled and, simultaneously, energy is detected and measured along a line of sight, so as to obtain an energy measurement. The line of sight for such energy detection lies within the stream of gas. Lastly, the energy measurement is processed to determine a value for a specified physical parameter.
This arrangement can permit measurement of certain parameters in the presence of interfering matter, such as slag, where conventional techniques would be inadequate.
The foregoing summary is intended merely to provide a brief description of the general nature of the invention. A more complete understanding of the invention can be obtained by referring to the claims and the following detailed description of the preferred embodiments in connection with the accompanying figures.